Seals and locks are used to secure a variety of objects, including containers and entrances to secure facilities. In addition to ordinary physical seals such as padlocks, seals have been developed that use electrical or fiber optic loops placed around or through an object to be secured. These electrical and fiber optic seals operate by detecting interruptions in electrical or optical signals propagating in the loop securing the object. When an interruption is detected, it is treated as an indication of a security breach. These seals are vulnerable, however, to sophisticated tampering techniques that can replicate the electrical or optical signal propagated through the loop to prevent a detection of interruption from occurring even when the seal is broken.